hi i got an 85 iroc that is tpi with the T-5 in it. the car was originally carbureted so i was wondering what gears i had in the rear axle? its got the 4 wheel disc brakes on it. and if i wanted to upgrade them how would i go about it? sorry if this feels like a dumb question but i don't know jack about axles and gears and all that. thanks.

 

Probably 3.23's (or 3.73's for the L69), but you won't really know until you pull the cover (no doubt needs a fluid change anyway) and take a peek. For much of what you need to know about 10-bolts, including brakes, check the following link:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

 

I think The L69 or LG4 were the only f-bodies to get 3.73 gears in the f-body; any LB9 would have a lower number like 3.23.

Like James said, with a used car, new gear oil & a quick count of the gear teeth are a good thing to do to be certain.